Method of incorporating photographic ingredients into photographic colloid compositions

ABSTRACT

A substantially water-insoluble photographic ingredient is incorporated into a hydrophilic colloid coating composition, used for instance in coating a photographic material such as a lightsensitive emulsion composition or the like, by dissolving such ingredient in at least one substantially water-immiscible organic solvent for the ingredient, admixing the organic solvent solution with water in the presence of a dispersing agent and in the absence of any hydrophilic colloid, removing from this admixture substantially all of the water-immiscible organic solvent used in dissolving the ingredient, and incorporating the aqueous dispersion obtained following such solvent removal in the desired hydrophilic colloid composition.

United States Patent Van Doorselaer et al.

METHOD OF INCORPORATING PHOTOGRAPI-IIC INGREDIENTS INTO PHOTOGRAPHIC COLLOID COMPOSITIONS Inventors: Marcel Karel Van Doorselaer, S-Gravenwezel; Gaston Jacob Benoy, Edegem; Jaak Pieter Van Vugt, Antwerp; Raphael Karel Van Poucke, Berchem, all of Belgiurn Afllilglltt'j (lcvm-rl-AUFA N.\ Mnrlscl. liclgium l'ilCllI Mar. 20, I970 Appl. No.: 21,470

Foreign Application Priority Data Mar. 20, 1969 Great Britain ..14,763/69 U.S. Cl ..96/100, 96/84, 96/109,

96/120 Int. Cl ..G03c 1/40 Field of Search ..96/100, 84

[56] References Cited UNITED STATES PATENTS 2,353,262 7/1944 Peterson et al. ..96/ 100 2,835,579 5/1958 Thirtle et. al. ..96/100 3,050,394 8/1962 Ben-Ezra et al. ..96/100 3,255,012 6/1966 Glockner et al. ..96/100 Primary Etaminer-J. Travis Brown Allurm'y -Willium J. Daniel (57] ABS'IRACT A substantially water-insoluble photographic ingredient is incorporated into a hydrophilic colloid coating composition, used for instance in coating a photographic material such as a light-sensitive emulsion composition or the like, by dissolving such ingredient in at least one substantially water-immiscible organic solvent for the ingredient, admixing the organic solvent solution with water in the presence of a dispersing agent and in the absence of any hydrophilic colloid, removing-from this admixture substantially all of the water-immiscible organic solvent used in dissolving the ingredient, and incorporating the aqueous dispersion obtained following such solvent removal in the desired hydrophilic colloid composition.

12 Claims, No Drawings METHOD OF-INCORPORATING PHOTOGRAPHIC INGREDIENTS INTO PHOTOGRAPHIC COLLOID COMPOSITIONS The present invention is concerned with a method ofincororating water-insoluble photographic ingredients into hydrophiliccolloid compositions, more especially with a methodof making dispersions in water of such ingredients from which they can be homogeneously distributed into hydrophilic colloid compositions.

In the manufacture of a photographic material numerous additives should be brought into operative association in one or more of the hydrophilic colloid layers of the said material. These additives include amongst others color couplers, maskforming compounds, dyes, e.g., filter dyes, antihalation dyes and sensitizing dyes, stabilizers, etc.

The methods according to which these additives are incorporated into the photographic hydrophilic colloid layers present numerous problems and much effort has been directed to solve these problems, particularly with regard to the incorporation in photographic emulsions of color couplers and mask-forming compounds.

By color coupler is meant any compound which in silver halide photography couples with an oxidized aromatic primary amino color developing agent to forma dye image. By maskforming compound is meant a compound which oxidatively emulsions remain immobile and do not wander or diffuse through the emulsion from their original site otherwise color separation will be imperfect and result in final dye images that are degraded. A common method employed to render color couplers and mask-formers non-diffusible in. hydrophilic colloid media is to provide them in the course of their synthesis with one or more ballast groups, e.g., a longstraight-chain or branched-chain aliphatic group such as an alkyl or alkylene group comprising from five to carbonatoms. The presence of this ballast group imparts to the molecule a hydrophobic character and therefore, these non-diffusible color couplers and mask-formers are generally also provided with one or more salt-forming groups, e.g., carboxy groups and preferably sulpho groups, so that these compounds can be dissolved in the photographic emulsions in the form of their soluble alkali salts.

However, the incorporation of these non-diffusible color couplers and mask-formers containing salt-forming groups, into aqueous hydrophilic colloid compositions frequently poses a number of difficultiesJ? or instance, some compounds are soluble only in highly alkaline solutions whichmight give riseto hydrolysis of possibly present ester groups or which, are too basic for use as such in conventional light-sensitive silver halide material, .where approximately .neutral solutions are most desirable, so that the hydrophilic colloid composition should be reacidified afterwards whereby flocculationmight occur and whereby inorganic salts are formed. Another difficulty attendant to this procedure of incorporating color couplers and mask-formers into'hydrophilic colloid media is due to the presence of the water-solubilizing groups more particularly the sulpho groups; these groups have a marked influence on the viscosity of the .hydrophiliccolloid medium, e.g., it is difficult to obtain, under the .same circumstances, reproducible viscosity values for hydrophilic colloid compositions comprising suchlike color couplers and on storing such compositions the viscosity undergoes further changes.

An alternate process of incorporating water-insoluble color couplers in photographic colloids makes use of a dispersion technique. According to this process substantially water-insoluble color couplers are dissolved in a volatile substantially water-immiscible solvent such as chloroform whereupon the solution formed is dispersed in extremely fine droplets in-the presence of a wetting or dispersing agent, into an aqueous nonlight-sensitive hydrophilic colloid medium, in particular aqueous gelatin, after which the solvent is removed by evaporation and the non-light-sensitive hydrophilic colloid composition comprising color coupler dispersed therein is admixed with the light-sensitive silver halide emulsion.

One of the advantages of the latter method is that color couplersand mask-formers may be used which contain no salt-forming groups. However, this process also poses difficulties. Removal of the solvent from the non-light-sensitive hydrophilic colloid composition may be difficult to effect and when any of the solvent isleft in the gelatin, its presence may be harmful, e.g., the color coupler or mask-former particles then'have the tendency to grow. Moreover, since the solution of color coupler or mask-former in the organic water-immiscible solvent should first be admixed with an aqueous non-sensitive hydrophilic gelatin composition before admixture with the light-sensitive silver halide emulsion in order to avoid that the water-immiscible solvent should be removed from the emulsion itself, that the emulsion itself should be excessively agitated for obtaining a sufficiently finely divided dispersion of the color coupler or mask-former solution in the emulsion which could cause fogging, and that a large bulk should be subjected to agitation an extra amount of gelatin is added to the light-sensitive emulsion which increases the coating thickness or conversely decreases the dye density which can be obtained for a given coating thickness. In addition thereto, the preformed non-light-sensitive gelatin compositions comprising color coupler or mask-former should be stored attemperatures below room-temperature and remelted at the moment of admixture with the light-sensitive emulsion. Further, preservatives such as phenol should be added to the gelatin composition in order to protect the gelatin against degeneratron.

, A new method has now been found for dispersing substantially water-insoluble color-coupling and mask-forming compounds into light-sensitive silver halide emulsions, which method does not show the disadvantages of the above dispersion technique.

Though this new method may be employed with particular advantage to introduce substantially water-insoluble non-diffusing color couplers and mask-formers into photographic light-sensitive emulsions it can also be used to introduce into light-sensitive emulsions other substantially water-insoluble photographic emulsion auxiliary components such as competing couplers, which are used in color photography as described in United Kingdom Pat. No. 861,138, filed Sept. 17, 1957, by Agfa A.G., light-screening dyes, sensitizing dyes, stabilizers etc. which normally are also preferably introduced from preformeddispersions in hydrophilic non-sensitive colloid compositions, as described e.g., for sensitizing dyes in Belgian Pat. No. 682,413, filed June 10, 1966, by Kodak S.A., to avoidv excessive agitation. of the emulsion and thus fogging.

Moreover, the method of thepresent invention can also be employed in the preparation of uniform dispersions of substantially water-insoluble photographic compounds in unsensitiz ed photographic colloid compositions. For example, it may be used in the production of water-permeable inter- .mediate layers in which it is desireduniformly to disperse a substantially water-insoluble light-absorbing filter or antihalation dye, competing couplers and other photographic active substances.

In accordance with the method of the present invention a substantially water-insoluble photographic component such as a color coupler, a mask-former, a competing coupler, a stabilizer and a dye, e.g., a light-absorbing or sensitizing dye is dissolved in a low-boiling substantially water-immiscible solvent for said component whereupon the solution formed is admixed with .water in the presence of a wetting or dispersing agent and the solvent is removed thus forming a stable extremely fine dispersion or suspension of the said componentin water. The dispersion of component in water thus formed can then be added to the hydrophilic colloid coating composition of the layer into which the said component should be present,

e.g., a light-sensitive silver halide emulsion layer or an intermediate layer.

By substantially water-insoluble photographic component must be understood a component of which not more than 3 percent by weight dissolves in water at room temperature C). The method of the invention has proved to be particularly valuable for the incorporation of components that do not contain water-solubilizable groups such as carboxy and sulpho groups.

The extremely finely divided dispersion or suspension of component in water, prepared as described above, has such a high stability that it is possible to create stocks of dispersions of photographic emulsion auxiliary components in water. Thus, the admixture of these water dispersions with a hydrophilic colloid silver halide emulsion can be delayed until the appropriate moment.

These dispersions of substantially water-insoluble photographic emulsion auxiliary components in water have the advantage over preformed non-light-sensitive gelatin compositions comprising such components dispersed therein, in that the said dispersions of components in water remain liquid whereas the gelatin compositions, even gelatin compositions comprising as low as 1 percent of gelatin, become solid and should be remelted at the stage of addition to the silver halide emulsion, that the dispersions of components in water can be stored at ordinary room-temperature, that the dispersions of components in water can comprise markedly higher concentrations of component than the preformed gelatin compositions and that no additional amount of gelatin is added to the emulsion so that no increase in coating thickness occurs, so that thin layers are obtained, which are less brittle, show improved flatness and result in better image sharpness. Moreover, removal of the substantially water-immiscible solvent from the dispersion in water is much easier to effect than removal from the gelatin composition.

It is rather surprising that, even in the absence of hydrophilic colloid such as gelatin the dispersions formed are stable enough to be stored as such, and that dispersions of much higher concentrations of components can be formed. it would be expected that upon removal of the solvent, precipitation (crystallization or flocculation) of the component would occur.

in the preparation of the dispersions of substantially waterinsoluble components in water in accordance with the invention usually a minimum of water is used in order to obtain dispersions as concentrated as possible which is particularly suitable for storing purposes. This minimum varies of course with each individual component and can be determined by trial. The amount of substantially water-immiscible solvent used is dependent on the solubility of the particular compound therein; it can vary within very wide limits but is also preferably restricted to a minimum.

The dispersion into water of the solution of the component in a water-immiscible solvent may be assisted by the use of high speed stirrers, homogenizers, colloid mills, ultrasonic wave generators, etc.

in accordance with the invention it is possible to incorporate the dispersions of the substantially water-insoluble components in water directly into the colloid coating composition of the layer into which said component is intended to be present. However, it is also possible to create stocks of the concentrated dispersions of the said components in water and to use parts of these stocks whenever required.

The said colloid coating compositions for forming a layer of a photographic material may of course contain in addition to the colloid carrier all sorts of other ingredients.

The amount of stored dispersion to be added to the colloid coating composition of the photographic layer is such that the substantially water-insoluble component is present in the resulting layer in the desired concentration. This amount is naturally dependent on the concentration of said component in said dispersion. In accordance with the present invention it was found possible in some instances to make stable dispersions of components in water comprising up to 30 percent of component.

The removal of the substantially water-immiscible solvent may be achieved for instance by evaporation, if necessary, e.g., for accelerating the removal, by applying reduced pressure and/or moderate heating, by steam-distillation (particularly when rather high boiling substantially water-immiscible solvents are used) etc.

The substantially water-immiscible solvents preferably have a solubility in water of at most 25 percent by weight at room temperature (20 C). Substantially water-immiscible solvents having a solubility in water comprised between 2 and 10 percent by weight at room temperature (20 C) are even the more favored. Moreover, said solvents preferably have a boiling point of at most 130 C and a sufficiently high vapor pressure so that they can still be removed readily from the dispersion by applying a vacuum of 500 to 10 mm Hg at a temperature of 25 to C.

Examples of suitable substantially water-immiscible solvents for use according to the present invention are methylene chloride, ethyl formate, n-butyl formate, ethyl acetate, n-propyl acetate, isopropyl acetate, butyl acetate, methyl propionate, ethyl propionate, carbon tetrachloride, sym.tetrachloroethane, 1,1,2-trich1oroethane, 1,2- dichloropropane, chloroform, n-butyl alcohol, diethyl ketone, methyl n-propyl ketone, diisopropyl ether, cyclohexane, methylcyclohexane, benzene, toluene, nitromethane, etc.

In order to facilitate dissolving of the substantially water-insoluble component it may be interesting in some cases to use mixtures of water-immiscible solvents or to use in conjunction with the substantially water-immiscible solvent a solvent which is miscible with water in all proportions. Of course, the water-miscible solvent should be completely miscible with the water-immiscible solvent used.

The water-miscible solvents are readily removed from the aqueous dispersion together with the water-immiscible solvents, unless they have too low a vapour-pressure to be removed with the water-immiscible solvents, in which case they are left in the dispersion of component in water from which they are incorporated into the hydrophilic colloid composition for forming a layer of a photographic material. The water-miscible solvents left in this hydrophilic colloid composition can be removed therefrom unless this is deemed unnecessary because they will have no disadvantageous effect on the physical or photographic properties by washing the chilled and thereby gelled colloid composition.

Examples of water-miscible solvents that are suitable for use in conjunction with the substantially water-immiscible solvents are methanol, ethanol, isopropyl alcohol, dimethyl sulphoxide, tetrahydrofuran, N-methyl-Z-pyrrolidone, dioxan, dimethyl formamide, dimethoxyethane, formamide, ethylene glycol, acetonitrile, acetone, butyrolactone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diacetone alcohol and tetrahydrothiophene-l ,l-dioxide.

Though, the wetting or dispersing agent employed in making the dispersion in water according to the present invention is generally added to the water into which the solution of component in water-immiscible solvent is dispersed, it can also be used in the step of dissolving the component in the organic solvent whereby it is possible to eliminate the use of a wetting or dispersing agent at the stage of dispersing the organic solution in water, or two different wetting agents can be used, one in each step.

A survey of dispersing agents and wetting agents, representatives of which can be applied in the method of the present invention are described by Gerhard Gewalek Waschund Netzmittel Akademieverlag Berlin 1962). Examples of suitable wetting agents are the sodium salt of N-methyl oleyltauride, sodium stearate, heptadecenylbenzimidazole sulphonic acid sodium salt, sodium sulphonates of higher aliphatic alcohols, e.g., Z-methyl-hexanol sodium sulphonate; sodium diiso-octyl-sulphosuccinate, sodium dodecyl sulphate, and tetradecyl benzene sulphonic acid sodium salt.

In making the dispersions in water of photographic substantially water-insoluble components according to the method of the present invention it was found very interesting to use as dispersing or wetting agent derivatives of said components or components of related structure comprising water-solubilizing groups, preferably sulpho groups in salt form. For instance, in the preparation according to the method of the present invention of a dispersion in water of a substantially water-insoluble naphthol color coupler for cyan a sulphonated naphthol color coupler can be successfully used as dispersing agent. Surprisingly, these sulphonated components have no influence on the viscosity of the hydrophilic colloid compositions into which the aqueous dispersions are to be incorporated, probably owing to micell-formation.

The amount of dispersing agent or wetting agent used in making the dispersions in water of photographic components according to the method of the present invention, may vary within very wide limits; it is generally comprised between 5 and percent by weight relative to the weight of component to be dispersed.

Although in applying the method according to the present invention for incorporating substantially water-insoluble components in hydrophilic colloid media, the use of gelatin as hydrophilic colloid is favored, other water-soluble colloidal materials or mixtures of them can be used too e.g., colloidal albumin, zein, casein, a cellulose derivative such as carboxymethyl cellulose, a synthetic hydrophilic colloid such as polyvinyl alcohol, poly-N-vinyl pyrrolidone, etc.

The following examples illustrate the present invention.

EXAMPLE 1 Ten g of the color coupler corresponding to the following structural formula @TCT-tmooomoo-Q The ethyl acetate was substantially removed by evaporation under reduced pressure of 200-400 mm Hg at 55 C leaving a stable dispersion of color coupler in water.

The dispersion of color coupler in water was then admixed with a conventional gelatine blue-sensitive silver halide emulsion ready for coating.

EXAMPLE 2 Ten g of the color coupler corresponding to the following structural formula ('fH @jCONH-(CHQu-CH:

was dissolved in ml of ethyl acetate. The solution was dispersed at- C, by means of a homogenizer in ml of distilled water (55 C) in the presence of 2 ml of ethyl acetate and 1.25 g of a wetting agent which is a color coupler having the following formula l SOaNa 5 stable dispersion of color coupler in water.

The dispersion was then admixed with a conventional redsensitized gelatino silver halide emulsion ready for coatingv EXAMPLE 3 One hundred ml of warm (55 C) distilled water, to which 6.25 ml of 20 percent aqueous solution of the wetting agent MERSOLAT H (trade name of Earbenfabriken Bayer A.G., Leverkusen, W.Germany for an alkane sulphonate wetting agent made by sulphochlorination and subsequent saponification of a mixture of saturated branched-chain as well as straight-chain hydrocarbons averaging 14 C-atoms obtained by hydrogenation of the so-called Kogasins, which are the hydrocarbon mixtures distilling in the range of 230320 C formed according to the Fischer-Tropsch hydrocarbon synthesis) had been added, were dispersed by means of a high speed stirrer in a warm (55 C) solution of 10 g of the color coupler according to US. Pat. No. 3,005,709 of Robert F.Coles issued Oct. 24, 196i, having the following structural formula:

in 30 ml of ethyl acetate.

The ethyl acetate was substantially removed as described in Examples 1 and 2 and the aqueous dispersion of color coupler in water formed was admixed by gentle stirring with a conventional red-sensitized gelatino silver halide emulsion ready for coating.

EXAMPLE 4 Ten g of the color coupler having the following structural formula:

was dissolved in 30 ml of ethyl acetate whereupon the solution formed was dispersed at 55 C by means of a high speed stirrer in 100 ml of warm (55 C) distilled water, in the presence of 12.50 ml of a l0 percent aqueous solution of the wetting agent corresponding to the formula given in Example 1 The ethyl acetate was substantially removed by evaporation under reduced pressure of 200400 mm Hg at 55 C, leaving a stable dispersion of color coupler in water.

The dispersion was then admixed by gentle stirring with a conventional green-sensitized gelatino silver halide emulsion ready for coating.

EXAMPLE on N l 1 3-0 ONH- S OgNH-(CH2)17 3 and 3 g. of the mask-forming compound corresponding to the formula:

Cans The ethyl acetate was removed by evaporation under reduced pressure of 200-400 mm Hg at 55 C leaving a stable homogeneously divided dispersion of mask-former and color coupler in water.

The dispersion formed was then admixed by gentle stirring with a conventional red-sensitized gelatino silver halide emulsion ready for coating.

EXAMPLE 6 Five g of the colorless coupling compound (competing coupler) corresponding to the following structural formula were dissolved at 60 C in ml of ethyl acetate. The solution formed was dispersed at 55 C by means ofa high speed stirrer in a mixture of 40 ml of distilled water and 7.5 ml of a 10 percent aqueous solution of the wetting agent of Example 1. The ethyl acetate was removed by evaporation under reduced pressure and the dispersion obtained diluted with distilled water to make 50 ml.

The dispersion in water of colorless coupling compound was then admixed with an aqueous gelatin coating composition for forming an intermediate layer between the red-sensitized and green-sensitized emulsion layers of a negative photographic multilayer color material. This multilayer material comprises in order on a support a red-sensitized silver halide emulsion layer comprising a color coupler for cyan, an intermediate layer comprising a colorless coupling compound, a green-sensitized silver halide emulsion layer comprising a color coupler for magenta, a yellow filter layer comprising colloidal silver and a spectrally unsensitized blue-sensitive silver halide emulsion layer comprising a color coupler for yellow.

EXAMPLE 7 Five g of the colorless coupling compound corresponding to the following structural formula were dissolved at 60 C in 15 ml of ethyl acetate. While still hot, the solution formed was dispersed by means of a high speed stirrer in a mixture of 40 ml of distilled water and 7.5 ml of a 10 percent aqueous solution of the wetting agent of Example l which was heated to 55 C. The ethyl acetate was removed by evaporation under reduced pressure and the dispersion left diluted with distilled water to make 50 ml.

The dispersion in water of the above colorless coupling compound was then admixed with a red-sensitized silver halide emulsion comprising a color coupler for cyan. This emulsion was coated on a support and then overcoated with a gelatin intermediate layer, a green-sensitized silver halide emulsion layer comprising a color coupler for magenta, a yellow filter layer comprising colloidal silver and a spectrally unsensitized blue-sensitive silver halide emulsion layer comprising a color coupler for yellow, thus forming a negative photographic multilayer color material.

We claim:

1. Method of incorporating a substantially water-insoluble organic solvent-soluble photographic ingredient into a hydrophilic colloid coating composition for forming a water-permeable colloid layer of a light-sensitive silver halide material which comprises the steps of dissolving said ingredient in at least one substantially water-immiscible organic solvent for said ingredient, admixing the organic solvent solution with water in the presence of a dispersing agent and in the absence of a hydrophilic colloid, removing from said admixture substantially all of each such organic solvent forming thereby a dispersion of said ingredient in said water, and incorporating the dispersion thus formed in said hydrophilic colloid coating composition.

2. Method according to claim 1, wherein said substantially water-immiscible solvent is soluble in water to the extent at most of 25 percent by weight at 20 C.

3. Method according to claim 1, wherein said substantially water-immiscible solvent has a boiling point of at most l30 C.

4. Method according to claim 1, wherein an organic solvent completely miscible with water is used together with said substantially water-immiscible solvent in order to dissolve said ingredient.

5. Method according to claim 1, wherein the said substantially water-immiscible solvent is removed by evaporation.

6. Method according to claim 1, wherein the said solvent is removed by evaporation under reduced pressure and/or by applying heat.

7. Method according to claim 1, wherein the dispersing agent is used in an amount comprised between 5 and 20 percent by weight relative to the weight of photographic ingredient.

ing dye and an organic stabilizing agent.

11. Method according to claim 1, wherein the said ingredient is a color coupler, a mask-former or a competing coupler containing a long straight-chain or branched-chain aliphatic group having from five to 20 C-atoms which renders the said ingredient fast to diffusion in the said hydrophilic colloid coating composition.

12. Method according to claim 1 wherein said dispersing agent is an anionic surfactant. 

2. Method according to claim 1, wherein said substantially water-immiscible solvent is soluble in water to the extent at most of 25 percent by weight at 20* C.
 3. Method according to claim 1, wherein said substantially water-immiscible solvent has a boiling point of at most 130* C.
 4. Method according to claim 1, wherein an organic solvent completely miscible with water is used together with said substantially water-immiscible solvent in order to dissolve said ingredient.
 5. Method according to claim 1, wherein the said substantially water-immiscible solvent is removed by evaporation.
 6. Method according to claim 1, wherein the said solvent is removed by evaporation under reduced pressure and/or by applying heat.
 7. Method according to claim 1, wherein the dispersing agent is used in an amount comprised between 5 and 20 percent by weight relative to the weight of photographic ingredient.
 8. Method according to claim 1, wherein the dispersing agent used is a derivative of the photographic ingredient carrying at least one water-solubilizing group.
 9. Method according to claim 1, wherein the said hydrophilic colloid coating composition is a light-sensitive hydrophilic colloid silver halide emulsion.
 10. Method according to claim 1, wherein the said substantially water-insoluble photographic ingredient is a member selected from the group consisting of a color coupler, a mask-former, a competing coupler, a light-absorbing dye, a sensitizing dye and an organic stabilizing agent.
 11. Method according to claim 1, wherein the said ingredient is a color coupler, a mask-former or a competing coupler containing a long straight-chain or branched-chain aliphatic group having from five to 20 C-atoms which renders the said ingredient fast to diffusion in the said hydrophilic colloid coating composition.
 12. Method according to claim 1 wherein said dispersing agent is an anionic surfactant. 